The present invention concerns electronic payment processes, particularly those in which the payment medium consists of a card comprising integrated circuits, generally referred to as a "smart card". As part of the smart project, it has been suggested that a "token" smart card be used to pay small sums of money by means of an electronic system.
It is well known that a smart card is a plastic medium whose dimensions conform to ISO standards 2894 and 3554. One or more electronic components are installed on this medium which can include, for example, a microprocessor and, especially, a data memory with a storage capacity of several hundred bits, usually of EPROM type. As far as the smart card itself is concerned, this memory is of EPROM type.
The processing performed within a "token" type smart card consists of making a payment unit, referred to as a "token", correspond to each bit in an area of a data memory. The value of this token will be determined according to the use of the card. For example, one bit can correspond to a token with a value of one franc.
Payment takes place in a "sales point" terminal equipped with a card reader in which a transaction is carried out by cancelling, in the data memory, the number of bits required for payment. The cancelling of a bit consists of electrically changing a binary element in the memory from a binary condition of "1" corresponding to a credit of one unit to a binary condition of "0" corresponding to zero credit, or vice versa. Since the data memory is of EPROM type, this change is electrically irreversible.
The above description of the basic system is simple and makes it possible to fully understand the principle of the token card.
Various improvements have later been added to this system in order to make it possible, for example, to reload units into the card and to reduce the consumption of bits. Indeed, in the basic system the number of bits cancelled is equal to the number of units to be consumed and we are limited to the payment of small sums in order to avoid using components which are, for the time being, too costly with respect to the goal sought.
Yet no irreversible token type system is currently known which makes it possible to modify the face value of the card during the course of the card's life.
There are, however, applications for which such a payment system is not suitable. This is particularly the case when the owner of the card has the possibility of receiving gains, which gains thus modify the face value of the card. Such a situation may occur especially in the case of gambling machines where tokens are consumed in order to run the machine and where the result of the game can lead to the winning of additional tokens by the player. This is an extension of the well known replay system in "pinball" type electric games.
With a token card of the type currently known, when the player obtains a gain he must leave the machine in order to receive a payment for the gain achieved. If he wishes to continue playing, he must then start a new game, spending the number of tokens in his card until they run out despite the gains obtained. These gains are usually only available in the form of a free card containing additional tokens or otherwise in the form of cash received from a pay desk. Such an interruption of the game is detrimental to both the player, who does not usually wish to stop, and to the operator of the machine, for whom it is desirable that players remain as long as possible in front of the machine.